One of the features which has become very popular in sailboat winches is the ability to shift the winch between different gear ratios simply by reversing the direction of rotation of an input member. The input member may be a winch handle which rotates a shaft or a crank mechanism which many crew members operate together to provide very high power to a single shaft.
An early two speed winch which shifts by reversal is shown in U.S. Pat. No. 3,145,974.
Three speed winches have been developed in which shifting is accomplished between both first and second and between second and third by reversal of an input. U.S. Pat. Nos. 3,728,914, 3,927,580, and 4,054,266, show such three speed winches in which the winch cascades through all three gears simply by two consecutive reversals.
Some three speed winches also have the ability to hold the winch in different conditions where the operator can select a pair of gears which are available alternately upon input reversal. U.S. Pat. No. 3,802,665 shows such a winch with a shift lever to select the availability of first and second or second and third.
Some winches have combinations of these features. For instance, U.S. Pat. No. Re. 30,881 and a winch installed on the twelve meter yacht American Eagle included both cascading through three gears on successive reversals and the ability to be operated in either the highest pair or the lowest pair of gear ratios depending on the position of a manual selector. The American Eagle winch has four gears with operation possible in first and second, third and fourth or second, third and fourth.
These winches have also been provided with devices known as range boxes which are manual gear shift mechanisms which are connected in series with a given winch to permit the winch to be operated in either a high range or a low range. A three speed winch with a two speed range box provides six available gear ratios.
One of the restraints which has confined the winch designer is the problem of providing winches with several pairs of gear ratios where the ratio between the gear ratios was different for different pairs. For instance, the designer might provide a three speed winch with gear ratios of 2:1 in first, 6:1 in second, and 24:1 in third. When this winch is operated in the first pair of gear ratios (first and second) for downwind work, the ratio between the gear ratios is 3:1, and when the winch is operated using the final second-third pair for up-wind work, the ratio between the two gear ratios is 4:1.
The designer can put a 1:2 range box in series with the winch to convert the winch for use in light air, and this would change the gear ratios to 1:1 in first, 3:1 in second, and 12:1 in third. However, the ratios between the gear ratios of the high pair and the final pair remain the same, 3:1 and 4:1, and this may be undesirable. For instance it may be desirable to have first gear raised to 1:1 for fast response with a spinnaker, but the 3:1 gear ratio paired with it may not be strong enough and the designer would rather have 5:1. It can't be done with a range box.